Methacrylamide polymers



United States Patent 25,645 CRYSTALLINE N-ALKYL ACRYLAMIDE ANDMETHACRYLAMIDE POLYMERS Donald J. Shields and Harry W. Coover, both ofKingsport, Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., acorporation of New Jersey No Drawing. Original No. 3,075,956, dated Jan.29, 1963, Ser. No. 756,279, Aug. 21, 1958. Application for reissue Apr.13, 1964, Ser. No. 367,913

12 Claims. (Cl. 26083.1)

Matter enclosed in heavy brackets II] appears in the original patent butforms no part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

This invention relates to the preparation of crystallizable acrylamideand methacrylamide polymers.

Substituted and unsubstituted acrylamides and methacrylamides areattractive materials for the preparation of resinous polymers because ofbeing readily available, inexpensive and easily polymerizable to formpolymers which can be molded, spun into strong and dyeable fibers,extruded into fibers and sheets and coated from their solutions, etc.Yet, in spite of their many excellent and unusual properties,polyacrylamides have not been widely used primarily because of theirsolubility in and sensitivity to water. It is quite apparent that awater-soluble polymer, although valuable in certain uses, is seriouslylimited in its applications and totally unsatisfactory for many uses.For example, there are small-scale uses for Water-soluble fibers in thepreparation of fine or noveltyweave fabrics where the water-solublefiber is used to impart strength to the fabric during the Weavingoperation and is then dissolved away. But, in general, a Watersolublefiber is useless as a general purpose fiber.

We have now discovered that highly crystalline, waterinsoluble,high-molecular weight acrylamide polymers can be prepared from monomersthat heretofore have been known to give only water-soluble polymers byusing certain compounds in combination as polymerization catalysts. Thepolymer products prepared according to our invention show decreasedwater sensitivity, greater hardness, higher density and improved heatresistance as compared to corresponding polyacrylamides prepared withconventional catalysts. The crystalline products can be readilytransformed by molding, extrusion or some other suitable method intoribbons, bands fibers, sheets or solid articles of improved toughness,hardness and heat resistance as compared with the correspondingamorphous polymers produced heretofore. The sheet materials of theinvention are useful as photographic film supports. If desired, theproducts can be modified by incorporation therein of fillers, dyes,pigments, etc.

It is accordingly, an object of the invention to provide novelwater-insoluble, high-molecular weight, highly crystalline acrylamidepolymers. Another object is to provide useful general purpose fibersthereof. Another object is to provide a process for preparing the saidcrystalline polymers. Other obpects will become apparent hereinafter.

In accordance with the invention, we prepare waterinsoluble,high-molecular weight, crystalline acrylamide and methacrylamidepolymers by contacting a monomeric compound represented by the followinggeneral formula:

wherein R and R each represents a hydrogen atom or an alkyl group offrom l-4 carbon atoms and R repre- "ice sents a hydrogen atom or amethyl group, alone or together with up to about 30%, based on the totalweight of the monomers, of a different acrylamide or methacrylamide,styrene, an alkyl ester of acrylic or methacrylic acid wherein the alkylgroup contains from 14 carbon atoms e.g. methyl acrylate, methylmethacrylate, etc., in the presence of a catalyst comprising a metalalkyl or aryl or a mixture of a metal alkyl or aryl and a transitionelement derivative at, 70200 C., but preferably from 70120 C., until themonomer has polymerized to give the highly crystalline polymer thereof.Ordinarily, a hydrocarbon reaction medium is employed, e.g. pentane,hexane, heptane or higheralkanes, toluene, and the like, although insome cases superior results are obtained by using coordinating solventssuch as dioxane, tetrahydrofuran, dimethoxyethane, and the like, eitheralone or in admixture with one of the preceding hydrocarbon solvents.from the reaction mixture by conventional methods, e.g. by evaporationof the solvent medium, by precipitation into a nonsolvent, washing,drying, etc. While the reaction can be carried out at any desiredpressure, the preferred method is to employ higher pressures, forexample, in a closed vessel such as an autoclave. The molecular weightof the polymer products can be varied but all are greater than 1,000 andpreferably greater than 10,000.

Suitable catalysts comprise metal alkyls of the general formula R M,wherein n represents an integer of 1-3, R represents an alkyl group offrom l-6 carbon atoms, e.g. methyl, ethyl, propyl, isopropyl, butyl,hexyl, etc. or an aryl group of 6-7 carbon atoms e.g. phenyl, o-tolyl,etc. groups and M represents a metal atom of groups I, II and III of theperiodic table of elements alone or in combination with one or morecompounds of the metals represented by groups 4B, 5B, 6B and 8, as wellas manganese group 7, of the periodic table of elements. When a catalystcombination is used, the preferred combinations are thetrialkylaluminums and alkyl lithiums with the halides of titanium,ziconium, vanadium, chromium and molybedenum, and more especiallytriethylaluminum and titanium tetrachloride. The proportions of thecatalyst components can be varied over a wide range, e.g. from ODS-10.0%or more, based on the total weight of monomer to be polymerized, butpreferably from 0.1 to 5.0% of the metal alkyl and from 0.1 to 5.0% ofthe said metal halides.

Suitable acrylamides and methacrylamides that can be polymerizedaccording to the process of the invention to give highly crystallinepolymers include acrylamide and its N-methyl, N-ethyl-N-propyl,N-isopropyl, N-butyl, N,N-dimethyl, N,N-diethyl, N,N-dipropyl,N,N-diisopropyl, N,N-dibutyl, etc. derivatives, and methacrylamide andits corresponding N-alkyl N,N-dialkyl substituted derivatives. Some ofthese materials such as N-t-butyl acrylamide give water-insolublepolymers under ordinary polymerizing conditions. In these few specialcases, the crystalline polymers exhibit, in addition to excellent waterresistance, the improved properties of higher hardness, heat distortiontemperature, etc. over ordinary polymers (prepared with conventionalcatalysts). Our novel process gives particularly outstanding results inthe case of mono-N-substituted acrylamides such .as N isopropylacrylamide. For example, when this compound is polymerized employingordinary free radical catalysts, the resulting polymer is water-solubleeven though its molecular weight is high. In contrast thereto, when thiscompound is polymerized according to the process of our invention, theresulting polymer is Water-insoluble even though the molecular weight issomewhat lower.

The following examples will serve to illustrate further the novelcrystalline polymers of the invention and the manner of preparing thesame.

The polymer products are separated 3 EXAMPLE 1 Into a 150 ml. pressurebottle purged with N were placed 80 ml. of dry heptane, 10 g. ofrecrystallized N- isopropylacrylamide, and 0.1 g. of acetyl peroxide.The mixture was tumbled at 45 C. for 15 hours. Evaporation of themoderately viscous reaction mixture gave a solid product that had aninherent viscosity of 1.0 and was completely soluble in water. Attemptsto mold the product were unsuccessful due to its high sensitivity towater. X-ray diffraction patterns showed it to be completely amorphous.

EXAMPLE 2 Into a 150 ml. pressure bottle purged with N were placed 80ml. of dry heptane, 10 g. of recrystallized N- isopropylacrylamide, 0.4g. of .triethylaluminum, and 0.1 g. of titanium tetrachloride. Themixture was tumbled at 45 C. for 15 hours. A white, heptane-insolublepolymer was obtained. It was completely insoluble in hot and cold water,had an inherent viscosity of about 0.2, according to X-ray diffractionpatterns was highly crystalline, and was molded .to give a hard, rigid,water-resistant plastic. It was also melt-spun, drafted and stabilizedto given an oriented, crystalline, water-insoluble fiber.

In place of the N-isopropyl acrylamide in above Example 2, there may besubstituted an equivalent amount of any other of the mentionedacrylamides and methacrylamides to give corresponding highlycrystalline, high-molecular weight polymers, for example, crystallinepoly-N-isopropylmethacrylamide, crystalline poly- N-methylacrylamide,crystalline poly-N-methylmethacrylamide, crystalline polymethacrylamide,crystalline poly-N-butylacrylamide, etc. Also, when a catalyst combination is used, the triethylaluminum and titanium tetrachloride can bereplaced with any other of the mentioned metal alkyls and metal halides,for example, a combination of triethylaluminum and zirconiumtetrachloride, trimethylaluminum and titanium trichloride, lithium butyland titanium trichloride, etc.

EXAMPLE 3 Into a 100 m1. pressure bottle purged with nitrogen wereplaced 10 ml. of dry heptane and g. of N-isopropylacrylamide. 2.27 g. ofa 6.15% solution of n-butyllithium in heptane was added, and then 0.16g. of anhydrous TiCl The mixture was agitated for one minute and wasallowed to stand at atmospheric pressure at 25 C. A White,heptane-insoluble polymer was obtained. It was completely insoluble inhot. and cold water, had an inherent viscosity of about 0.3 according toX-ray difiraction patterns was highly crystalline, and was molded togive a hard, rigid, water-resistant plastic. It was also melt spun,drafted, and stabilized to give an oriented, crystalline,water-insoluble fiber.

EXAMPLE 4 The procedure of Example 3 was followed using 0.64 g. ofsodium naphthalene and 0.68 g. of anhydrous zirconium tetrachloride. Asimilar polymer having an inherent viscosity of 0.45 was obtained.

EXAMPLE 5 The procedure of Example 3 was following using 2.76 g. of16.3% triethylaluminum solution in heptane and 3.62 g. of titaniumtrichloride. A similar polymer having an inherent viscosity of 0.27 wasobtained.

EXAMPLE 6 Into a 100 ml., 3-necked flask equipped with dropping funnel,thermometer, and stirrer, and cooled in a Dry Ice bath was placed 40 g.ofdry dimethoxyethane 111d 20 g. of N-isopropylacrylamide. 6.1 ml. of a10.5% solution of n-butyllithium in hexane was added iropwise withstirring. An exothermic reaction resulted and the polymer partiallyseparated from solution. The product was treated with methanol to removecatalyst residues, and 11 g. of a polymer having an inherent viscosityof 0.38 was obtained. It was completely insoluble in hot and cold water,and according to Xray diffraction patterns was highly crystalline. Itwas melt spun, drafted, and stabilized to give an oriented, crystalline,water-insoluble fiber.

EXAMPLE 7 EXAMPLE 8 To a ml, 3-necked flask equipped with droppingfunnel, thermometer, and stirrer and cooled in a Dry Ice bath to 60 C.were added 40 g. of dry heptane and 10 g. of N-isopropylacrylamide. 6ml. ofa 10.5% solution of n-butyllithium in heptane was added dropwisewith stirring. A solid white polymer formed in the flask. The polymerwas washed with methanol to remove catalyst residues, and 8 g. ofpolymer having an inherent viscosity of 0.3 was obtained. It wasinsoluble in hot and cold water and according to X-ray diitractionanalysis had a high degree of crystallinity. It could be spun intowater-insoluble fibers.

EXAMPLE 9 Into a 100 ml. pressure vessel purged with nitrogen wereplaced 30.6 ml. of dry heptane, 6 ml. of 1,2-dimethoxyethane, 20 g. ofN-isoprop-ylacrylamide, 405 g. of 16.3% triethylaluminum in dry heptane,and 0.34 g. of vanadium trichloride. An exothermic reaction occurred,and the solution became somewhat viscous. After heating at 70 for 16hours, the polymer was isolated by treatment with methanol and hydrogenchloride. The polymer had an inherent viscosity of 0.2 and was insolublein hot and cold water. X-ray analysis indicated that it had a highdegree of crystallinity. It was spun into crystalline, water-insolublefibers.

If desired, one or more different monomers can be copolymerized with theN-isopropylacrylamide. The second monomer can be a different acrylamideor methacrylamide monomer or it can be any of several monoethylenicallyunsaturated monomers. Forexample, the N-isopropylacrylamide can becopolymerized with styrene to give a highly crystalline copolymer or itcan be copolymerized with methyl methacrylate to give a copolymer ofslightly reduced crystallinity. This behavior is illustrated in, butshould not be limited by, the following example.

EXAMPLE 10 The procedure of Example 1 was followed using 8 g. ofrecrystallized N-isopropylacrylamide, 2 g. of stryrene, 0.5 g. oftriethylaluminum, and 0.2 g. of titanium tetrachloride. The mixture wastumbled at 65 for 15 hours. A white, heptane-insoluble polymer wasobtained. It was completely insoluble in hot and cold water, had aninherent viscosity of about 0.8, and according to X-ray diffractionpatterns was highly crystalline. It could be molded to give hard, rigid,water-resistant plastics.

The improved properties of the polymers of the inven tion which, inaddition to decrease water sensitivity, includes increased hardness,higher density, and improved heat resistance, are probably related tothe crystallinity 6.1 ml. of a 10.5% solution of nof the polymer. Thepreparation of crystalline or crystallizable polymers is well known inthe case of hydrocarbon type monomers such as ethylene, propylene,styrene, and the like. However, the literature is replete withreferences stating that monomers containing functional groups such as anamide carbonyl poison the usual catalysts that lead to crystallinepolymers. According to our new process, however, crystallinepolyacrylamides can be formed with surprising ease and in good yieldsand under exceptionally mild reaction conditions.

The invention has been described in detail with particular references topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

What we claim is:

1. A crystalline linear addition polymer of an acrylamide compoundrepresented by the following general formula:

wherein R and R each represents a member selected from the groupconsisting of a hydrogen atom and an alkyl group of from 1 to 4 carbonatoms and R represents a member selected from the group consisting of ahydrogen atom and a methyl group, said polymer having a crystallineX-ray diffraction pattern and a molecular weight greater than 1000 asdetermined from the intrinsic viscosity thereof.

2. A crystalline linear poly-N-isopropylacrylamide having a crystallineX-ray diffraction pattern and a molecular weight greater than 1000 asdetermined from the intrinsic viscosity thereof.

3. A crystalline linear poly-N-isopropylmethacrylamide having acrystalline X-ray diifraction pattern and a molecular weight greaterthan 1000 as determined from the intrinsic viscosity thereof.

4. A crystalline linear poly-N-methylacrylamide having a crystallineX-ray diffraction pattern and a molecular weight greater than 1000 asdetermined from the intrinsic viscosity thereof.

5. A crystalline linear poly-N-methyl methacrylamide having acrystalline X-ray diffraction pattern and a molecular Weight greaterthan 1000 as determined from the intrinsic viscosity thereof.

6. A crystalline linear addition copolymer consisting of at least 70% byweight of N-isopropylacrylamide and not more than 30% by weight ofstyrene and having a crystalline X-ray diffraction pattern and amolecular weight greater than 1000 as determined from the intrinsicviscosity thereof.

7. A process for preparing a crystalline linear addition polymer havinga. crystalline X-ray diffraction pattern and a molecular weight greaterthan 1000 as determined from the intrinsic viscosity thereof whichcomprises contacting at --70 to 200 C. monomeric material selected fromthe group consisting of (a) a compound represented by the followinggeneral formula:

wherein R and R each represents a member selected from the groupconsisting of a hydrogen atom and an alkyl group of from 1 to 4 carbonatoms and R represents a member selected from the group consisting of ahydrogen atom and a methyl group, and (b) a mixture consisting of atleast by weight of a compound represented by the said general formulaand not more than 30% by weight of a different compound selected fromthe group consisting of a compound represented by the said generalformula, styrene, an alkyl acrylate wherein the said alkyl groupcontains from 1 to 4 carbon atoms and an alkyl methacrylate wherein thesaid alkyl group contains from 1 to 4 carbon atoms, with a catalystselected from the group consisting of (1) a metal alkyl represented bythe general formula wherein n represents an integer of from 1 to 3, Rrepresents a member selected from the group consisting of an alkyl groupcontaining from 1 to 6 carbon atoms, a phenyl group and a tolyl groupand M represents a metal atom selected from Groups I, II and III ofMendeleeifs Periodic Table of elements and (2) a mixture of said metalalkyl (1) with a halide of a metal selected from the group consisting ofgroups 4B, 5B, 6B and 8 corresponding to the periodic table of elementson pages 448 and 449 of the Handbook of Chemistry and Physics, 40thedition, Chemical Rubber Publishing Company, and manganese.

8. The process of claim 7 wherein the said monomeric material isN-isopropylyacrylamide and the said catalyst is n-butyllithium.

9. The process of claim 7 wherein the said monomeric material isN-isopropylyacrylamide and the said catalyst is a mixture consisting oftriethylaluminum and titanium tetrachloride.

10. The process of claim 7 wherein the said monomeric material isN-isopropylyacrylamide and the said catalyst is a mixture consisting oftriethylaluminum and vanadium trichloride.

11. The process of claim 7 wherein the said monomeric material isN-isopropylacrylamide and the said catalyst is a mixture consisting ofn-butyllithium and titanium trichloride.

12. The process of claim 7 wherein the said monomeric material is amixture consisting of at least 70% by weight of N-isopropylacrylamideand not more than 30% by weight of styrene and the said catalyst is amixture consisting of triethylaluminum and titanium tetrachloride.

References Cited in the file of this patent orthe original patent UNITEDSTATES PATENTS 2,748,029 Spear et al. May 29, 1956 2,790,789 Miller Apr.30, 1957 2,827,447 Nowlin et al Mar. 18, 1958 2,842,474 Pratt July 8,1958 2,932,633 Juveland Apr. 12, 1960' FOREIGN PATENTS 538,782 BelgiumDec. 6, 1955 OTHER REFERENCES Schildknecht: Vinyl and Related Polymers,Wiley and Sons (1952), pages 314-322.

